<?php

/*
	Question2Answer (c) Gideon Greenspan

	http://www.question2answer.org/

	
	File: qa-include/qa-app-blobs.php
	Version: See define()s at top of qa-include/qa-base.php
	Description: Application-level blob-management functions


	This program is free software; you can redistribute it and/or
	modify it under the terms of the GNU General Public License
	as published by the Free Software Foundation; either version 2
	of the License, or (at your option) any later version.
	
	This program is distributed in the hope that it will be useful,
	but WITHOUT ANY WARRANTY; without even the implied warranty of
	MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
	GNU General Public License for more details.

	More about this license: http://www.question2answer.org/license.php
*/

if (!defined('QA_VERSION')) { // don't allow this page to be requested directly from browser
    header('Location: ../');
    exit;
}


function qa_get_blob_url($blobid, $absolute = false)
    /*
        Return the URL which will output $blobid from the database when requested, $absolute or relative
    */
{
    if (qa_to_override(__FUNCTION__)) {
        $args = func_get_args();
        return qa_call_override(__FUNCTION__, $args);
    }

    return qa_path('blob', array('qa_blobid' => $blobid), $absolute ? qa_opt('site_url') : null, QA_URL_FORMAT_PARAMS);
}


function qa_get_blob_directory($blobid)
    /*
        Return the full path to the on-disk directory for blob $blobid (subdirectories are named by the first 3 digits of $blobid)
    */
{
    if (qa_to_override(__FUNCTION__)) {
        $args = func_get_args();
        return qa_call_override(__FUNCTION__, $args);
    }

    return rtrim(QA_BLOBS_DIRECTORY, '/') . '/' . substr(str_pad($blobid, 20, '0', STR_PAD_LEFT), 0, 3);
}


function qa_get_blob_filename($blobid, $format)
    /*
        Return the full page and filename of blob $blobid which is in $format ($format is used as the file name suffix e.g. .jpg)
    */
{
    if (qa_to_override(__FUNCTION__)) {
        $args = func_get_args();
        return qa_call_override(__FUNCTION__, $args);
    }

    return qa_get_blob_directory($blobid) . '/' . $blobid . '.' . preg_replace('/[^A-Za-z0-9]/', '', $format);
}


function qa_create_blob($content, $format, $sourcefilename = null, $userid = null, $cookieid = null, $ip = null)
    /*
        Create a new blob (storing the content in the database or on disk as appropriate) with $content and $format, returning its blobid.
        Pass the original name of the file uploaded in $sourcefilename and the $userid, $cookieid and $ip of the user creating it
    */
{
    if (qa_to_override(__FUNCTION__)) {
        $args = func_get_args();
        return qa_call_override(__FUNCTION__, $args);
    }

    require_once QA_INCLUDE_DIR . 'qa-db-blobs.php';

    $blobid = qa_db_blob_create(defined('QA_BLOBS_DIRECTORY') ? null : $content, $format, $sourcefilename, $userid, $cookieid, $ip);

    if (isset($blobid) && defined('QA_BLOBS_DIRECTORY'))
        if (!qa_write_blob_file($blobid, $content, $format))
            qa_db_blob_set_content($blobid, $content); // still write content to the database if writing to disk failed

    return $blobid;
}


function qa_write_blob_file($blobid, $content, $format)
    /*
        Write the on-disk file for blob $blobid with $content and $format. Returns true if the write succeeded, false otherwise.
    */
{
    if (qa_to_override(__FUNCTION__)) {
        $args = func_get_args();
        return qa_call_override(__FUNCTION__, $args);
    }

    $written = false;

    $directory = qa_get_blob_directory($blobid);
    if (is_dir($directory) || mkdir($directory, fileperms(rtrim(QA_BLOBS_DIRECTORY, '/')) & 0777)) {
        $filename = qa_get_blob_filename($blobid, $format);

        $file = fopen($filename, 'xb');
        if (is_resource($file)) {
            if (fwrite($file, $content) >= strlen($content))
                $written = true;

            fclose($file);

            if (!$written)
                unlink($filename);
        }
    }

    return $written;
}


function qa_read_blob($blobid)
    /*
        Retrieve blob $blobid from the database, reading the content from disk if appropriate
    */
{
    if (qa_to_override(__FUNCTION__)) {
        $args = func_get_args();
        return qa_call_override(__FUNCTION__, $args);
    }

    require_once QA_INCLUDE_DIR . 'qa-db-blobs.php';

    $blob = qa_db_blob_read($blobid);

    if (defined('QA_BLOBS_DIRECTORY') && !isset($blob['content']))
        $blob['content'] = qa_read_blob_file($blobid, $blob['format']);

    return $blob;
}


function qa_read_blob_file($blobid, $format)
    /*
        Read the content of blob $blobid in $format from disk. On failure, it will return false.
    */
{
    if (qa_to_override(__FUNCTION__)) {
        $args = func_get_args();
        return qa_call_override(__FUNCTION__, $args);
    }

    return file_get_contents(qa_get_blob_filename($blobid, $format));
}


function qa_delete_blob($blobid)
    /*
        Delete blob $blobid from the database, and remove the on-disk file if appropriate
    */
{
    if (qa_to_override(__FUNCTION__)) {
        $args = func_get_args();
        return qa_call_override(__FUNCTION__, $args);
    }

    require_once QA_INCLUDE_DIR . 'qa-db-blobs.php';

    if (defined('QA_BLOBS_DIRECTORY')) {
        $blob = qa_db_blob_read($blobid);

        if (isset($blob) && !isset($blob['content']))
            unlink(qa_get_blob_filename($blobid, $blob['format']));
    }

    qa_db_blob_delete($blobid);
}


function qa_delete_blob_file($blobid, $format)
    /*
        Delete the on-disk file for blob $blobid in $format
    */
{
    if (qa_to_override(__FUNCTION__)) {
        $args = func_get_args();
        return qa_call_override(__FUNCTION__, $args);
    }

    unlink(qa_get_blob_filename($blobid, $format));
}


function qa_blob_exists($blobid)
    /*
        Check if blob $blobid exists
    */
{
    if (qa_to_override(__FUNCTION__)) {
        $args = func_get_args();
        return qa_call_override(__FUNCTION__, $args);
    }

    require_once QA_INCLUDE_DIR . 'qa-db-blobs.php';

    return qa_db_blob_exists($blobid);
}


/*
	Omit PHP closing tag to help avoid accidental output
*/